People are generally aware of the most common causes of hallucinations, like schizophrenia and a really high fever. But lesser known are the more rare causes; here are six you probably haven't heard about.

Why It's Hard To Maintain Eye Contact When Talking

A person who doesn’t look others in the eye while talking is often perceived as lying, bored, awkward, or lacking in confidence, but two researchers from Kyoto University in Japan suggest something else may be going on. A new study in Cognition says eye contact and verbal processing “share cognitive resources,” so doing both at the same time puts a lot of demand on the brain.

The verbal processing includes both retrieving and selecting words from one’s vocabulary, and the researchers tested these functions during different amounts of eye contact. Participants looked at faces — some with their eyes directed toward them and others with their eyes averted — while playing a word association game. The 26 people had to say words that immediately came to them after seeing other words of varying difficulty, judged based on the number of possible responses to choose from, and the researchers noted how long it took them to answer and how much they broke eye contact.

If you have a hard time looking someone in the eye while talking, it could be your brain trying to protect itself.Image courtesy of Pixabay, public domain

The study says responses on the more difficult words were slower if eye contact was maintained. Keeping that eye contact while searching for a word, it suggests, puts too much demand on the brain.

“Most everyone knows that maintaining eye contact with another person while speaking can sometimes be difficult — at times, the urge to look away becomes overwhelming,” according to a press release about the findings. Sometimes when this occurs “we are trying to keep our brains from overloading” by focusing entirely on just the verbal processing.

The researchers say the results show that fully understanding communication requires understanding how nonverbal “channels” can interfere and interact with the verbal.